An Internet Protocol television (IPTV) and an evolved multimedia broadcast multicast service (eMBMS) generally use a multicast technology to effectively reduce pressures on devices and bandwidths. In the IPTV and the eMBMS, a multicast source (source) of an operator center sends traffic in a multicast manner to a provider edge router (PE) connected to a user side, so that the PE may further forward the traffic to the user side.
IP multicast protocols mainly include an Internet Group Management Protocol (IGMP) that is used for host registration and used for a user side host to send an IGMP join packet to a PE to perform registration, and a Multicast Routing Protocol that is used for multicast routing and forwarding. The Multicast Routing Protocol generally uses Protocol Independent Multicast (PIM). The PIM Protocol is independent of a unicast routing protocol provided that the unicast routing protocol can generate a routing entry.
In the prior art, multicast only fast reroute (MoFRR) is generally used for implementing fault switchover, so as to reduce service interruption caused by a fault of an Internet Protocol (IP) network that bears multicast traffic. MoFRR is applied to a PE node, and requires that two paths that are completely separate in physical topology (topo) exist from a PE to a multicast source. The PE sends a PIM join (join) packet to an upstream node of either of a primary (primary) path and a secondary (secondary) path to join a multicast routing network, and then receives, by using both of the two paths, multicast traffic sent by the multicast source. Normally, after receiving the traffic, the PE performs reverse path forwarding (RPF) check according to the primary path; if traffic received by the primary path passes the RPF check, the traffic received by the primary path is forwarded to a user side (Receiver); if traffic received by the secondary path does not pass the RPF check, the traffic received by the secondary path is directly discarded. When the primary path is faulty, the PE performs RPF check according to the secondary path, so that the traffic received by the PE from the secondary path can pass the RPF check and is not discarded, so as to ensure that the user side can normally receive traffic.
However, once the PE does not have a primary path and a secondary path to the multicast source that are completely separate in physical topo, the foregoing solution cannot be used for performing fault switchover.